Vyborg-Petrozavodsk Offensive

The Vyborg-Petrozavodsk Offensive (10 June-9 August 1944) was a strategic offensive by the Soviet Leningrad and Karelian Fronts against Finland in Karelia during the Continuation War of World War II. The offensive was only a partial strategic success for the Soviets, who overran East Karelia and Vyborg, but the offensive persuaded Finland to break off relations with Germany and end its participation in the war.

Background
After the failure at the Battle of Kursk, Finland had sought to make peace with the Soviet Union, but the negotiations had broken down. In the fall of 1943 Finland had a highly skilled and durable army of 350,000 troops who faced just 180,000 Red Army troops of poor quality. In northern Lapland the German 20th Mountain Army was some 180,000 strong, more than a match for the Soviet troops on the Karelian Front. The Finns, however, had no illusions about the likely outcome of the war. While their president, Risto Ryti, pledged to the Germans not to sign a separate peace with the USSR, they were determined to sit out the conflict.

Offensive
For his part, Stalin was eagle to settle with Finland before Operation Bagration. Having reinforced the Red Army's Karelian and Leningrad Fronts, Stalin ordered them to go on the offensive in June 1944 against the vulnerable southeast flank of the Finnish army. The Red Army captured East Karelia and Vyborg (Viipuri), but the fighting reached a stalemate as the Finns clung on thorughout the summer. On 4 August 1944, Marshal Carl Gustaf Emil Mannerheim, the hero of the Winter War of 1939-1940 and the Finnish commander-in-chief, succeeded Ryti as head of state and repudiated the latter's pledge. Moscow then agreed to resume negotiations with Finland on the condition that Mannerheim broke off relations with Germany and the 20th Mountain Army left Finnish territory by 15 September. The offensive failed to destroy the Finnish forces in Karelia, but the offensive forced Finland from the war and to accept Soviet peace terms.